Amplitude modulated continuous wave time-of-flight range cameras suffer from an inherent depth measurement error due to systematic error contributors, e.g. from so-called wiggling error for phase estimation with non-sinusoidal modulation signals. This is due to higher harmonics present in both signals which are not accounted for in the model or measurements. These and other systematic depth-dependent errors are generally corrected by employing a correction function based on frequency and depth dependent calibration data.
Thus, any three-dimensional image (3DI) sensor should be calibrated and corrected with thereby determined depth dependent correction values when used for depth measurement to account for existing systematic errors (e.g., wiggling errors). Currently this calibration has to be done for each final ToF camera or camera module by using an expensive and complicated calibration rig during an expensive and complicated calibration procedure.
For example, existing 3DI depth calibration is done by expensive and time consuming calibration system, with complicated procedure and sample handling. One way to achieve this calibration is by using a linear translation stage for manual calibration at defined distance steps between the ToF camera and a target plane.
The existing calibration procedure is not considered to be ideal due to time consuming depth calibration, complicated setup (also production and calibration of existing calibration setup) and complicated and time-consuming sample handling.
Therefore, an automated calibration procedure that simplifies the effort and reduces costs on the depth calibration for ToF 3DI cameras and sensor chips may be desired.